1. Field of the Invention
The present invention relates to a magnetic recording medium.
2. Brief Description of the Prior Art
An attempt has been made to improve the durability of the magnetic layer on a non-magnetic supporting film by modifying the surface of magnetic or magnetizable powder materials used in the magnetic layer by a treatment with a silane coupling agent. The silane coupling agent is an organic silicon compound having two or more different reactive groups in one molecule. One of the reactive groups is one capable of forming a chemical bond with an inorganic material, that is, magnetic or magnetizable powder material and may include, for example, methoxy, ethoxy and silanol groups. The other is one capable of forming a chemical bond with an organic material and may include, for example, vinyl, epoxy, methacryl, amino and mercapto groups. The silane coupling agent is found effective in treating magnetic or magnetizable powder material itself. It has however drawbacks in association with the binding with the organic material.
The conventional silane coupling agents have been employed only with a limited group of binders. The magnetic layer formed using such silane coupling agent should be treated within a limited range of reaction temperatures because of the heat resistance of a base film, such as a polyester base. Where a catalyst is used to accelerate the reaction, the pot life of a magnetic paint is rendered so short that a problem with its industrial applicability is encountered. A further drawback resides in that where the reactive groups in the silane coupling agent are allowed to react with the organic material in the magnetic paint to form chemical bonds, the orientation of the magnetic or magnetizable powder material is rendered poor.